• Dr Alex Baker

The James Webb Space Telescope: Unlocking the hidden truths of the Universe

On Christmas Day, 2021, NASA launched the world’s largest observatory to date: the James Webb Space Telescope (JWST). Despite a nerve-wracking 344 SPOFs (single points of failure) spanning a craft the size of a tennis court, JWST was successful in its trajectory and has now reached its home at L2—a gravitationally stable spot known as a Lagrange point, some 1.5 million kilometres away from Earth.

Inspired by an iconic image of distant galaxies shimmering against an endless sea of black—taken from JWST’s predecessor, the Hubble Space Telescope—the team at NASA embarked upon a mission to try and study even further back into the universe’s origins; 300 billion light years into the cosmic soup of the dark ages, to be precise. However, the course of the multi-decade-long project, despite its numerous technological advancements, achievements, and promising future, has certainly not been smooth sailing.

James Webb Space Telescope sculpture concept
James Webb Space Telescope sculpture

James Webb Space Telescope’s Extensive Technical Requirements

  • The telescope has an incredibly complex origami-like structure. Over the course of its ascent to L2, the 18 honeycomb-shaped cryogenic mirrors of its upper section had to unfold and fan out to form a large mirror with a final size of 6.5 metres. According to JWST’S Optical Telescope Element Manager, Lee Feinberg, each of the 18 Hexagonal mirror pieces of the upper section had to align within one five-thousandth the width of a human hair.

  • The telescope requires extreme temperatures to function. Whilst its upper sun-facing portion has to remain consistently at 85℃, the other side is kept at approximately −233°C. To maintain such homeostasis, the two sections are separated by a precisely positioned five-layered sunshield, each successive layer cooling the space beneath.

  • In order to block out infrared background ‘noise’, the JWST had to utilise the world’s coolest element, helium, for its mid-infrared instrument’s cryocooler (a refrigerator designed to reach cryogenic temperatures). The technology surrounding the mid-infrared instrument, or MIRI, marked a huge stepping stone in the field of astronomy. The longer the wavelength of infrared, the cooler the detector needs to be. Given the ambitious 14 billion year observational path of the JWST, its detector system has to stay at less than 7 kelvin to operate efficiently, −266°C!


Parts of the James Webb Space Telescope being constructed

What will the James Webb Space Telescope be observing?

Since its launch, JWST’s journey has fortunately gone exceptionally smoothly. Some 300 observing programmes are planned to take place throughout the telescope’s lifetime, although these observations won’t commence until June of this year. To date, NASA have already been able to match the telescope’s first evaluation images to each of the 18 telescopes that make up the JWST, showing that the cameras are working effectively. Whilst the images are not yet crystal clear, and have to undergo a process known as ‘global alignment’ in order to reach optimum clarity, things are looking promising for the future of JWST.


Exoplanets

Exoplanets are planets that exist outside of our Solar System. One branch of JWST’s observing programmes will be focusing on the atmosphere of exoplanets, and potential foundations of life that exist on these planetary bodies.


One way that this information will be gathered is called the Transit Method: taking observations of light dimming from a star as its planet passes between us and the star. The Webb will also do spectroscopy (measuring the intensity of light at different wavelengths) as well as taking coronographic observations (using a telescopic attachment that blocks out direct light emitted from stars, thereby unveiling nearby objects in the process).


Very, very distant galaxies

As fantastic as The Hubble is, it isn’t able to detect the first galaxies. The JWST is optimized with unparalleled infrared technology to detect faint infrared light from 14 billion years in the past, looking at a part of space that we have never seen before. According to NASA, it will be able to see ‘the light of a bumblebee at the distance of the moon’. Compared to its predecessor, the JWST has a fifteen times wider field of view on its main camera and collects six times the light, meaning that if all things go to plan, we will be even closer to establishing the make-up of the unique origins of the universe. In order to make these discoveries, the JWST’s camera will stare deeply into one patch of sky for extended periods of time, gathering as much light and information as possible.


Dark Matter and Dark Energy

Dark matter and dark energy remain the greatest mysteries in the realm of astrophysics. The team at JWST rather ambitiously aim to unravel some of these dark secrets, potentially bridging the gap between Hawking’s decades-old notions and a deeper understanding of antimatter. This is hoped to be achieved by taking images to observe disturbances in what is known as gravitational lensing. These images will seek to make the invisible, visible.


Much like a fun-house mirror, space and time can be curved/warped. Since gravity bends the path of light, and light travels through spacetime, light can dip and curve in the presence of large objects. This process of distortion is called gravitational lensing. The JWST aims to detect the nature of gravitational lensing patterns from distant galaxies, furthering our understanding of both the structure and expansion of the universe.


One major theory concerning the nature of dark matter’s role in the Big Bang comes from Hawking’s primordial black holes theory—the idea that dense regions that existed in the hot and hyper-compact early universe became the first black holes. The JWST may serve to prove or completely debunk this idea, as well as competing alternatives; for instance, the theory about black holes resulting from the collapse of stars.


Many astronomy experts are keen to see whether or not black holes existed since the beginning of time, or whether they came to fruition only after the first generation of stars died out. If the JWST manages to detect the first light of the universe, and thus the stars which formed mere moments after the Big Bang, this question may be answered at last.

Black hole concept image

Let’s Wait and See

Pushing the boundaries of human ingenuity, the James Webb Space Telescope stands as the most impressive machinery that NASA has perhaps ever created. Let’s hope the JWST continues to progress our understanding of the universe in the myriad ways the scientific community is eagerly waiting for; or at the very least, and alike the twinkling stars above, provide some exciting, light-bulb moments of scientific revelation that might just change the course of history as we know it.